{"id":"CVE-2026-30927","aliases":["GHSA-7pfv-hr63-h7cw"],"url":"https://o3.security/vulnerability/CVE-2026-30927","summary":"Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter","details":"## Vulnerability\n\nIn `modules/events/events_function.php`, the event participation logic allows any user who can participate in an event to register OTHER users by manipulating the `user_uuid` GET parameter.\n\nLine 47: `$getUserUuid = admFuncVariableIsValid($_GET, 'user_uuid', 'uuid', ...)`\nLine 424: `if ($event->possibleToParticipate() || $participants->isLeader($gCurrentUserId))`\n\nThe condition uses `||` (OR), meaning if `possibleToParticipate()` returns true (event is open for participation), ANY user - not just leaders - can specify a different `user_uuid` and register/cancel participation for that user.\n\nThe code then operates on `$user->getValue('usr_id')` (the target user from user_uuid) rather than the current user.\n\n## Impact\n- Register unwilling users for events (potential harassment/spam)\n- Cancel other users' event participation\n- Manipulate event participant counts and comments\n- If events have participation limits, fill slots with unwanted registrations\n\n## Fix\nFor non-leader users, force `user_uuid` to the current user:\n```php\nif (!$participants->isLeader($gCurrentUserId)) {\n    $getUserUuid = $gCurrentUser->getValue('usr_uuid');\n}\n```","published":"2026-03-09T23:03:55.824Z","modified":"2026-10-28T02:30:28.932817108Z","cvss":null,"epss":{"score":0.00253,"percentile":0.16529,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"admidio/admidio","fixedVersion":"5.0.6"}],"fix":{"url":"https://github.com/Admidio/admidio/commit/e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e","label":"Admidio/admidio@e47f70c"},"references":[{"type":"ADVISORY","url":"https://github.com/Admidio/admidio/security/advisories/GHSA-7pfv-hr63-h7cw"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30927.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-30927"},{"type":"REPORT","url":"https://github.com/Admidio/admidio/issues/1985"},{"type":"FIX","url":"https://github.com/Admidio/admidio/commit/e47f70cc3cbcdb39635fdbaaef02d19f604b8c3e"},{"type":"PACKAGE","url":"https://github.com/Admidio/admidio"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:28.932817108Z"}}